Meiosis – HSC Biology

Learn.

What is meiosis? | Facts | yourgenome.org
Diagram of meiosis from your genome

Interphase is not apart of meiosis or mitosis and it occurs to prepare the cell for division. The cell prepares through growing, replicating it’s DNA and preparing to divide.

Prophase is the first step in meiosis, DNA has been replicated so it pairs up at the centromere. Additionally, the chromatin in the cell is condensed and the nucleolus disappears.

Metaphase is when the chromosomes are lined up at the equator of the cell, the genetic information is at its second most condensed stage.

Anaphase involves the pulling apart of the chromosomes into sister chromatids by the spindle fibres which are protrusion from the centriol which are found at both ends of the cell. The daughter chromatids are therefore transported to opposite poles of the cell.

Telophase is the final stage in mitosis and it involves the uncoiling of chromosomes to form chromatin. Hence preparing the genetic material to direct metabolic activities for the new cells. Additionally, the spindle breaks down, and new nuclear envelopes envelop the DNA.

Additionally, cytokinesis occurs which involves the cell membrane being pinched inwards for the cell hence forming to new cells.

Meiosis differs in that the aboves processes Prophase, metaphase, anaphase, telephase and cytokenesis occurs twice. Therefore, 4 haploid cells form from 1 diploid cell. These haploid cells contain half the amount of DNA as the parent cell. These form gametes (sperm cells and egg cells), which can later combine and form a diploid cell which will replicate through mitosis to form a new organism.

Master.

Question 1.

A student states:

‘All cells in the body are genetically identical’

Evaluate the validity of the statement, explain your reasoning [3 marks]

Question 2.

Compare and contrast mitosis and meiosis

Question 3.

Question 28b) from 2019 HSC Exam

Question 4.

Answers.

Question 1.

The majority of an organisms cells are genetically identical, however, gametes are not genetically identical as well as cancer cells. 

Meiosis – 1 diploid parent cell forms four genetically different haploid granddaughter cells. This genetic diversity can come about from crossing over between metaphase and anaphase.

Mitosis – 1 diploid parent cell forms two genetically identical daughter cells.

Question 2.

ReasonMarks
Provides 2 differences:Prophase, metaphase, telophase and anaphase occur twice in meiosis and once in mitosisMitosis has 2 genetically identical daughter cells and meiosis has four genetically different granddaughter cells2
Provides 2 similarities: Both result in formation of daughter cellsBoth involve DNA doubling up at some point2

Question 4.

HSC question 2020 Q19

A

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